The present invention relates to motor vehicle speed sensors.
Transmission-mounted vehicle speed sensors have been provided to sense the speed of a vehicle. Some transmission speed sensors have electromagnetic sensing structures that include a thin wire wound around a post to create a coil. In turn, the coil is electrically coupled to a pair of terminals by a pair of electrical leads. To render an appropriate circuit, a shunt resistor is installed across the terminals. Typically, the electrical leads are connected to the terminals and then, in a separate process step, the shunt resistor is attached to the terminals by either crimping or spot welding them together. The extra step to connect the shunt resistor to the terminals consumes time and increases costs.
Accordingly, the present invention recognizes the need for a speed sensor in which the shunt resistor is connected in such a manner that minimizes manufacturing time and costs.
A vehicle speed sensor includes a sensor housing and a sensing structure disposed within the sensor housing. The sensing structure includes a coil wound around a base and a shunt resistor that is molded into the base and electrically connected to the ends of the coil.
As envisioned in the particularly preferred embodiment set forth below, the coil is connected to two rigid electrical terminals and the shunt resistor is disposed on the base between the terminals and closely spaced therefrom. The shunt resistor has two ends and the sensor further includes at least two electrical leads that are wrapped around the terminals and the ends of the shunt resistor.
Preferably, the vehicle speed sensor includes a connector housing that is coupled to the sensor housing and a connector that is supported by the connector housing and electrically coupled to the terminals. The connector housing forms a socket around the connector, and the socket is sized to engage a complementarily-shaped and sized electrical connector. In a preferred embodiment, the connector housing defines a first axis and the sensor housing defines a second axis that is orthogonal to the first axis.
Also in a preferred embodiment, the connector housing is formed with at least one o-ring groove and an o-ring is disposed within the o-ring groove such that it establishes a seal between the sensor housing and the connector housing. The sensor housing further has an outer wall with an abutment flange that abuts a transmission housing.
In another aspect of the present invention, a vehicle speed sensor includes a sensor housing with a sensing structure disposed within. The sensing structure has a base and a coil. At least two terminals are supported on the base of the sensing structure and a shunt resistor is molded onto the base between the terminals to electrically connect them.
In yet another aspect of the present invention, a shunt resistor is electrically coupled to at least two terminals within a vehicle speed sensor. This is accomplished by providing a sensing structure that has a base, a coil, and at least two electrical leads electrically connected to the coil. A shunt resistor having two ends is insert molded within the base of the sensing structure so that it is juxtaposed with the terminals. The electrical leads are then wound around the ends of the shunt resistor and the terminals so that each end of the shunt resistor is electrically connected to one terminal.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: